Closure operator



Jan. 18, 1949. P. M. GRIFFIN CLOSURE OPERATOR 2 Sheets-Sheet 1 Filed Sept. 21, 1943 Jan. 18, 1949. P. M. GRIFFIN 2,459,695

' CLOSURE OPERATOR Filed Sept. 21, 1945 2 Sheets-Sheet 2 7 5 z /4 l" A 25 1" 25 I r J9 //v vgxv TOR Percy M 6/77/92? A 7' TORNEY Patented Jan. 18, 1949 UNITED STATES PATENT OFFICE CLOSURE OPERATOR Percy M. Griffin, Albany, N. Y., assignor to Cansolidated Car-Heating Company, Inc., Albany, N. Y., a corporation of New York Application September 21, 1943, Serial No. 503,302

My invention relates to fluid actuated closure operators and particularly to hydraulically actuated operators for opening and closing ,car doors, bus doors and the like.

For many years brakes on commercial passenger carrying vehicles have been actuated by compressed air and, probably, because a supply of compressed air must be available for the opera-, tion of such brakes, thedoor opening and closing devices have been operated by compressed air from the same source. Such devices operate at relatively low air pressure,'say around 100 pounds per square inch,.and, because considerable power must be developed the air actuated operators have been comparatively large.

With the increasing use of hydraulic brakes and the like which require a source of supply of liquid, usually oil, under high pressure, it has become desirable to provide an hydraulically actuated door operator which may draw its power from the same source as the hydraulic brake actuating mechanism, and thus avoid the necessity of providing both a source of compressed air 4 Claims. (Cl. 121-44) and a source of liquid under high pressure. Furthermore, it is desirable, in many instances, to.

provide safety devices which prevent the doors of a passenger vehicle from being opened when the vehicle is in motion with the brakes off and the problem is considerably simplified where both doors and brakes are actuated by the same medium. By utilizing high pressure, say of the order of two thousand pounds per square inch, a great deal of power can be generated by comparatively small mechanisms with parts moving through comparatively short distances and thus the size of the closure operators may be substantially reduced. However, due to the high pressures involved the present designs of air actuated closure operators are not at all suited for hydraulic operation because of the special problems encountered in the change over involving leakages of liquid under such high pressures through gaskets and the like and the extremely close tolerances to which reciprocating pistons and the like must be fitted to provide positive operation. Aside from the fact that leakages result in substantial loss of pressure, efliciency and positiveness of operation, they are particularly objectionable in door operators since such devices are ordinarily positioned over the doors operated thereby and through which passengers enter and leave the vehicle.

The general object of my invention is to provide an hydraulically actuated closure operator of simple design in which pressure leaks are sub- 2 stantially eliminated and which is so designed that substantial leakage past the pistons and otherwise can be eliminated without the necessity of having the pistons, cylinders and other parts fitted to such extremely close tolerances that they are unduly expensive to produce. Another object is to provide an hydraulically actuated closure operator of the differential pressure reciprocating type in which the cylinders are separate units so that in case of defects which develop either during the fabrication of the cylinders or during the operation thereof it is not necessary to discard both cylinders to remedy adefect in one. Another object is to provide anovel unitary means in such a device for regulating the rate of closure opening, closing, or both, which will be free from the usual fine adjustments, provide a fixed rate of operation throughout indefinitely long periods without servicing, and which is quickly interchangeable with a similar unit to provide sub stantially any other operating rate that may be desired. A furtherobject is to provide a device of this character which is easy to manufacture, assemble, test and service.

With these, objects in view myinvention includes the novel elements and the combinations and arrangements thereof described below and illustrated in the accompanying drawings in which-- Fig. 1 is a small scale plan view of my closure operator showing the control valve and fragmentary portions of the pipe system associated therewith;

Fig. 2 is a sectionalplan view taken in a hori- Fig. 5 is an end view of a split bushing;

Fig. 6 is a section of a plug adapted to be threaded into the end of the smaller cylinder;

Fig. 7 is a fragmentary top view of my closure operator; and v Fig. 8 is a section of Fig. 7 inthe plane 88.

Referring to the drawings and particularly to Figs. 2, '7 and 8 my device comprises a central element or block I through which extendthe 3 be keyed. The bushing l is pressed tightly into the bore 6 while the bushing 8 is pressed lightly into the bore and prevented from turning therein by means of the dowel H. The bottom of the bore is sealed with a cap l2. Between the pinion and the bushings l and 8, which are preferably the Oilite type, are steel thrust washers l3 and I l. The bushings and shaft assembly are held in place by means of the cover plate or cap I which is secured to the top of the central element by means of screws 45. To disassemble this part of the device it is necessary only to remove the cap l5 and pull the shaft 9 with the bushing 8, the

of the element. 7 r

The central element I is also provided'with'a horizontal bore I! which intersects the bore 6.

- exhausting stroke. It comprises the pipe-thread- 4 in the same manner as the like parts in the cylinder 22.

As illustrated the heads of the pistons 31 and 39 contact the ends of the rack l8 and thus may reciprocate the rack and turn the pinion Ill.

The valve element 35, a unitary, plug-like structure, which is threaded into the head of the large: cylinder 22. constitutes a. nieansfor automatically checking the rate of movement of the piston 3| as it approaches the end of its fluid edportion 34 and a tubular portion 46 which extance into' the'hollow, cup-like piston 3|.

thread' adapted to form a high pressure tight and which is adapted to form a bearing for the reciprocating rack l8, The rack teeth engage the teeth of the pinion and thus the rack is prevented from' turning in the bore H. The central element l is also provided with an oil drain l9 which is drilled fromthe outside of the central element to intersect the bore 51'- In order tofacilitate connecting pipes to carry the drainage in either direction from the-closure operator 2. crossdrain is drilled to intersect the drain l9. After thedrains are drilled the outside end of the drain I! is'plugged, as shown at (see Fig. 8).

From the foregoing it will be apparent that axial movement of the rack 18 will cause the pinion ID to rotate in one direction or the other and thus turn the shaft 9.

'In order to reciprocate the rack I provide two separate cylinders with pistons therein, one on each side of the central element l; Referring particularly to Fig. 2, the cylinder 22 is a unitary, cup-like castingprovided with the flanges 23 and 24" which abut the central member I and which are secured thereto by means of the cap screws 25 and 25. The end of the cylinder '22 which is adjacent the central element 1 is bored out to receive thesteel washer 2! and counterbored toreceive the neoprene washer 28. Adjacent its open end the cylinder 22. is also bored out to receive the glandelement 29' and the packing 30. The gland element 29 abuts the Washer 21 which in turn abuts the neoprene washer 28 which liesin contact with the side of. the central. element 1 and serves both as a gasket and also as a cushioning. element for the adjacent piston as will be hereinafter explained. The length of the gland element 29 and. the thickness of the packing, and the washers 21 and 28 aresuch that,

.neoprene gasket forming a tight seal between the end of the cylinder and the central element. The head 32 of the cylinder is provided with a threaded opening 33 adapted. to receive the pipethreaded portion 34 of a; valve element 35 which will be hereinafter described 1 Secured to the opposite side of the central element by means of cap screws 44 and 45 is a second cylinder 36 which is an integral casting and provided in the head with a. threaded opening 31 adapted to receive the pipe-threaded plug 33 (see Fig. 6) This cylinder is of smaller diameter than the cylinder 22 and'hasa piston 39 mounted. to reciprocate therein. The packing 40, the gland 4|, a steel washer 42'and a neoprene-'-washer' or gasket 43" are associated with'the cylinder 35 joint with apipe. 48 (see Fig, 1) through which liquid is conveyed to the interior of the cylinder 22; The interior of the tubular portion 46 of the valve element 35 communicates directly with the pipe 48 through the small passage 49 and also with the interior of the cylinder 22 through the openings 55 and 5t. The interior of the cylinder also communicates with the passage: 49 through the very small-passage 52. i

. Slidably mounted to reciprocate within the: tubular portion 46. is. a needle-valve element-53 adapted to' seat in and. close. the passage 49. The element 53 is normally urged. away-from its seat: by means of a comparatively light, hell-- cal spring 54. The inner end'of the tubular portion is partially closed by the split bushing 56 (see Figs. 2 and: 5) and. the stem. of. the plunger 51: ismounted to reciprocate in this bushing. Between the head 58 of the plunger and the adjacent end of the needle-valve element is a comparatively stiff, helical spring 59.. Normally; neither the spring 54 nor the spring 59 is compressed, but both of them may be compressed to yieldingly force the needle-valve element into its seat by the contact of the inside of the head of the piston 3twith the stem of plunger 51 as itv moves to the left on its. fluid-exhausting. stroke.v In orden to bleed the cylinders 2-2 and Y36, respectively, I provide eachof them on the-top and near the head; thereotwith'small openings which are normally sealed by means of theplugs and 6t, respectivelytsee Figs. 3 and 4). Referring particularly to Figs. 1, and 2 it is tobe understood that. the pipe .62 connects at all timeswith an accumulator (not shown)- contaiming the operating liquid under high pressure, say around zooow ouna er square inch,. while the; pipe 63' connects at. all times with the. snmpof.

' the 1 accumulator from which the. liquid is pumped into the accumulator. 64 is athree-way valve: which, in one position, will permit liquid to flow; therethrough from the pipe 62 through the pipe into pipe 48 and thus into the. larger. cylinder. Whenthe-valveisin thispositioni'pipe G3 is shut ofi at the valve; In the. other; position oithe-valvef Myths flow. of-liquid fromrp p 35(15'011151 citatthea valve and communication isv provided. between pipes. 43 and. 63: so that fluid in: therlargeir cylinder- 22 rnay dischargedtherefromgthrouglr the pipes.

48- and 53 into the sump.

- It will be apparent iromithe foregoing that,- since the diameterof piston. exceeds the 'diam-I etc: of piston139,.--wherr valve 64 is. positionedtd admit fluid to cylinder 22', although the-pressure per square inch of pistonarea. is identical in-both.-' cylinders, nevertheless piston 3! will be moved; toward the small'encylindenfl; andfluid inacylinder 39 vwiikue iorcedcutfiorithe cylinder through; theplug 38 2115 into-theipipei G2: wneetnewawe 64 is positioned tocut offcommunication between pipes 48 and 65 and provide communication between pipes 48 and 63 the constant pressure on the head of piston 39 will force it towards cylinder 22 and fluid will be discharged or exhausted from cylinder 22 through the passages 49 and 52 into pipe48; i.

Referring particularly vto Figs. 1 and 2, if it be assumed that the closure operator is-being usedito Open and closethe doors of abus or car and that the doors are closed, piston 39 will be as far to the right as it can be moved. That is to say the right hand end of the piston 3| will be near'or in contact'with the washer 21, the rack l8 will have movedlas far to the right as possible, and cylinder .22 will be in communication with. the accumulator through the passages 52 and 49, pipe 48, valve 66 and pipe 65.. To open the doorsvalve 64 is merely turned to such a position as will. ex.- haust fluid from cylinder 22 which will cause piston 39 to force piston 3land rack l8 to the left until the head of piston 39 contacts washer 42. Then, to close the doors, valve 54 is merely turned to the position where communication between pipes 48 and 65 is established and communication cut off between pipes 48 and 63.

On the opening movement, when piston 39 is being forced to the left, cylinder 22 initially discharges into the sump through both openings 49 and- 52. However, as piston 3! moves to the left the-head.thereof will contact the stem of the plunger and force it to theleft. The movement oithe plunger 51 to the left will force the needle-valve 53 into its seat against the compression of the light spring 54 and, thereafter, as the plunger 5'! is moved further to the left,.spring 59 will be compressed. When the needle-valve 53 is in its seat the rate of discharge of fluid from cylinder 22 will be sub'stantiallyreduced because it can then bedischarged only through the small passage 52. Thus, the rate of movement of the piston 3| will be correspondingly reduced sothat, just before the door is fully--open'ed. its rate of movement will be substantially checked and slamming open of the doors will be prevented;

The sizes of the passages 49 and 52 depend on the pressure of the liquid in the accumulator, the difference in cross-sectional area between the piston 3i and the piston 39, and the time interval within which it is desired to open and close the door. Ordinarily a vehicle door should open in about one and one-half second and completely close in about two to two and one-half second. However, with my device substantially any rates of opening and closing can be provided by selecting a plug 38 and a valve element 35 having fluid passages therethrough of the appropriate size. It will be noted that there are no adjustments of any kind to be made in order to eflect and maintain any opening and closing rates that may be desired. The manufacturer may carry in stock plugs such as 38, and valve elements such as 35, having various combinations of passages therethrough and thus provide a closure operator having any desirable rate of opening and closing; it being necessary only to fit the operator with the proper size plug and valve element. It should also be noted that my device diflers materially from those checking devices in which the cross-sectional area of the outflow passage is positively controlled by an element cooperating directly with the piston, as illustrated in U. S. Letters Patent No. 2,114,334, granted to Conklin on April 19, 1938. In such devices it is obvious that, since the passage is positively closed or reduced in area by the movement of the piston, it cannot be restored to its normal full-flow area until the piston has moved some distance in the reverse direction, and since the rate of piston movement in the reverse direction depends upon the rate at which the actuating fluid can enter the cylinder, the reverse movement of .the piston, in its initial stage, is retarded to the same degree that its direct movement is checked in the final stage thereof. In my device, pressure of the entering fluid in passage 49 will immediately force the needle valve 53 into open position and thus .at once provide a passage of full-flow area. for the inflowing fluid.

: The difficulty in maintaining free from leaks a device of this character which operates under extremely high pressure is recognized and the device. has been designed with this clifliculty in mind. It is possible by means of pipe-threaded joints to produce perfectly tight connections but it is almost impossible to do this by designs involving the use of gaskets which are prone to leak or even to blow out under high pressure. It will be noted that in my design pressure leaks are eliminate dby reason of the fact that the pressure ends of the cylinder have only pipe-threaded connections. As illustrated, the cylinders are closed by pipe-threaded plugs, which are preferred to caps, but pipe-threaded caps engaging the outer ends of the cylinders might be employed. The neoprene gaskets 28 and43 are not subjected to liquid pressure, and any liquid which leaks past the piston will be drained oil to the sump of the accumulator'through the drains l9 and 29.

Furthermore it will be noted that, because the cylinders in my design are separate units any leak or defect which develops in either one of them can be readily corrected merely by removing that cylinder alone and replacing it with a new one. It is apparent also that, if desired, a valve element such as that shown at 35, may be used in the smaller cylinder where it is desired to checkthe closing movement of the door or, in both cylinders where. it is desired to check both the opening and closing movements thereof. Thus, I have provided a closure operator of extremely simple design which is adapted to operate under very high liquid pressures and which can be readily serviced and maintained in perfect operating condition.

While I have described my invention in its preferred embodiment it is to be understood that the words which I have used are words of description rather than of limitation and that changes within the purview of the appended claims may be made without departing from the true scope and spirit of my invention.

What I claim is:

1. In a fluid actuated closure operator of the differential pressure type including a cylinder having a piston mounted for reciprocation therein, a unitary valve for reducing the rate of fluid discharge from said cylinder as said piston approaches the end of its fluid-exhausting stroke comprising an elongated element having a tubular portion and provided with means adapting it to be fixedly secured to said cylinder with said tubular portion extending therein and also with passage means for the flow of fluid therethrough to and from said cylinder, means slidably mounted in said tubular portion for reducing the effective cross-sectional area of said passage means and means, including resilient means, separate from said area-reducing means adapted to cooperate with said piston and with said area-reducing means for actuating the latter as said piston approaches the end of its fluid-exhausting stroke.

' 2. In afluid actuated closure operator of? the difierential pressure, type including a cylinder having a piston mounted for-reciprocation therein; a unitary valve for reducing the. rate. oi. fluid dis charge: from said cylinder as said piston. approaches the end of its fluid-exhausting, stroke comprising an elongated element. having a tubular portion and provided with. means. adaptingv it: to be. fixedly secured to said cylinder with said tubular portion extending therein and. also. with passage means for the flow' of fluid .therethrough to and from said cylinder, means slidably mounted in said tubular portion for reducing the effective cross-sectional area of said passage means and means, including resilient means, mounted in said tubular portion and slidable therein. independently of said area-reducing means adapted to cooperate with said piston and with said areareducing. means for actuating the. latter as said piston approaches the end of its'fluid-exhausting stroke.

3. In a fluid actuated closure operator of the differential pressure type including a cylinder having a piston mounted for reciprocation therein; a unitary valve for reducing the rate. oiv fluid discharge from said cylinder as said piston approaches the end of its fluid-exhausting stroke comprising an elongated tubular element provided with means for securing it in said cylinder and. with at least two passages for the flow of fluid therethrough to andv from. said cylinder, a movable passage closing element adapted to close one of said passages, means normally urging said closing element to passage-open position, means adapted to cooperate with said piston for moving said closing element into passage-closed. position as said piston approaches the end of its fluidexhausting stroke, and yielding means positioned between and cooperating with both saidclosing element and said piston cooperating. means.

4. In a. hydraulically actuated motor of the d'iiferentialpressure type including a cylinder having' a piston mounted for reciprocation therein, a device for reducing the rateof fiu-id discharge from said cylinder as said piston approaches the tirelyclosing the same, and means independent. of I saidvalve. element but-recuperating therewithand with. said piston for effecting a seating" of. said valve element as said piston armroaches. the end of. its. fluid-exhausting'stroke said last mentioned means: including means. adapted to yield under pressure of fluid entering said passage means to efiect. an unseating of. said valve element. and restore; said passage. means to. itsful'lfiow capacity irrespective of the position of said. piston.

. PERCY M. GRIFFIN.

REFERENCES CITED The following references are of record. in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,799,366 Heinkel 'Apr. 7, 1931 1,833,216 Hanna Nov. 24, 1931 1,852,507 Davis Apr. 5, 1932 1,891,312 Knecht' -Dec; 20,, 1932 1,957,697 Conway May 8; 1934 1,971,048 Parsons Aug; 21 1934' 2,114,334 Conkli'n Apr. 19, 1938 2,115,845 Forman May 3, 1938 2,192,175 Ballard Mar. 5, 1940 2,262,432 Rudder Nov; 11, 1941 2,338,845 Gunner Jan. 11', 1944 2,342,001 Magnuson Feb. 15, 1944 FOREIGN PATENTS Number Country Date 677,908 France Dec. 19, 15929 

